Valves are used in myriad systems to control the flow of fluid to and from one or more systems or components. In many systems, these valves are operated using some sort of remotely controlled valve actuator assembly. Such actuator assemblies include a torque source that is used to move the valve between its open and closed positions. The torque source may be, for example, a hydraulic actuator, a pneumatic actuator, or an electrical actuator, such as solenoids, and motors.
Many valve actuator assemblies are an agglomeration of several components and/or subassemblies that are interconnected and incorporated into the final valve assembly. Although these valve actuator assemblies are safe and reliable, each presents certain drawbacks. For example, a valve actuator assembly constructed of numerous individual components and/or subassemblies may increase overall weight, size, and cost of the valve to which the actuator assembly is coupled. In addition, the relatively large number of parts may, among other things, adversely impact the overall reliability and performance of the valve actuator assembly.
One of the several individual components and/or subassemblies that make up the above-described actuator assemblies is a position sensor, which is used to supply a signal representative of the position of the valve. In many instances, the position sensors that are used are contamination sensitive and/or cannot be exposed to system fluids without incurring damage. Hence, to protect the position sensor from contamination and/or exposure to system fluids, dynamic seals are employed. Although dynamic seals are reliable in inhibiting contamination and fluids from reaching the position sensor, the seals can also create significant frictional torque. As a result, the operating torque margin for the actuator assembly torque source may be reduced, which may result in the need for a larger torque source, which may in turn increase valve weight and cost.
Hence, there is a need for a valve actuator assembly that is not constructed of numerous individual components and/or subsystems, and/or does not use dynamic seals or other potential sources of frictional torque, and/or reduces valve and valve actuator assembly weight, and/or reduces valve and valve actuator assembly cost, and/or improves valve and valve actuator reliability as compared to present valve and valve actuator assemblies. The present invention addresses one or more of these needs.